Content addressed storage (CAS) devices store typically fixed content in a storage server typically accessed via a network. An example is the Centera™ CAS device made and sold by EMC™ Corporation of Hopkinton, Mass. Typically, an application sends data to the CAS device to be stored, the CAS device determines a storage location by calculating a “content address” (CA) based at least in part on the content to be stored, after which the CAS device stores the content in the selected location and returns the content address to the application that sent the data. The content address is used like a claim check to enable the storing application (or, in theory, another application to which the CA has been provided) to retrieve (and in some cases perform other limited operations, e.g., delete) the previously stored content.
Under the typical approach described above, an application must be configured to receive the content address and track a mapping between the content address and a local object identifier (e.g., a file name and/or path) by which the stored data object is known on the local system on which the application is running. This limits the use of CAS devices to those applications configured to maintain such a mapping and consumes time and resources on the local system. For some types of application, the functionality for maintaining such a mapping may already exist or be relatively easy to incorporate, but for other applications the required level of data tracking may become an obstacle to using a CAS device for storage.
Therefore, there is a need for a way to enable applications to use a CAS device for storage without requiring that the application maintain a mapping between the content address associated with the data on the CAS device and the local object identifier (e.g., local file system name and/or path) of the data object on the local system on which the application is running.